/**
 * (C) Copyright IBM Corp. 2010, 2015
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 */


package com.ibm.bi.dml.runtime.matrix.data;

import java.io.IOException;

/**
 * Any data output that is intended to support fast serialization / write
 * of entire blocks should implement this interface. On write of a matrix block
 * we check if the output stream is an implementation of this interface, if
 * yes we directly pass the entire block instead of value-by-value.
 * 
 * Known implementation classes:
 *    - CacheDataOutput (cache serialization into in-memory write buffer)
 *    - FastBufferedDataOutputStream (cache eviction to local file system)
 * 
 */
public interface MatrixBlockDataOutput 
{
	/**
	 * Writes the double array of a dense block to the data output. 
	 * 
	 * @param len
	 * @param varr
	 * @throws IOException
	 */
	public void writeDoubleArray(int len, double[] varr) 
		throws IOException;
	
	/**
	 * Writes the sparse rows array of a sparse block to the data output.
	 * 
	 * @param rlen
	 * @param rows
	 * @throws IOException
	 */
	public void writeSparseRows(int rlen, SparseRow[] rows) 
		throws IOException;
}
